test on UST seems not correct in w3iogomd.F90

[mickaelaccensi]

Describe the bug
AUX1 and AUX2 should only be written if UST(ISEA) and ASF(ISEA) is not UNDEF

        ELSE IF ( IFI .EQ. 5 .AND. IFJ .EQ. 1 ) THEN
          DO ISEA=1, NSEA
            IX     = MAPSF(ISEA,1)
            IY     = MAPSF(ISEA,2)
            IF ( MAPSTA(IY,IX) .EQ. 1 ) THEN
              AUX1(ISEA) = UST(ISEA) * ASF(ISEA) *        &
                   COS(USTDIR(ISEA))
              AUX2(ISEA) = UST(ISEA) * ASF(ISEA) *        &
                   SIN(USTDIR(ISEA))
            ELSE
              AUX1(ISEA) = UNDEF
              AUX2(ISEA) = UNDEF
            END IF
          END DO
          WRITE ( NDSOG ) AUX1
          WRITE ( NDSOG ) AUX2

To Reproduce
running regtests ww3_tp2.6, ww3_ufs1.2, mww3_test_04 should show differences

Expected behavior
IX = MAPSF(ISEA,1)
IY = MAPSF(ISEA,2)
IF ( MAPSTA(IY,IX) .EQ. 1 ) THEN

should be replaced by :

IF ( UST(ISEA) .NE. UNDEF .AND. ASF(ISEA) .NE. UNDEF ) THEN

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Add any other context about the problem here.

[JessicaMeixner-NOAA]

@mickaelaccensi I agree those variables should not be calculated unless those variables are defined. Do we need the additional if MAPSTA(IY,IX) .EQ. 1 as well as the additional check?

I made a branch with your update here: https://github.com/jessicameixner-noaa/ww3/tree/bug/initvalueust

and here are the regtest output:

**********************************************************************
********************* non-identical cases ****************************
**********************************************************************
mww3_test_03/./work_PR1_MPI_e                     (1 files differ)
mww3_test_03/./work_PR3_UNO_MPI_e                     (1 files differ)
mww3_test_03/./work_PR2_UQ_MPI_e                     (1 files differ)
mww3_test_03/./work_PR2_UNO_MPI_e                     (1 files differ)
mww3_test_03/./work_PR2_UNO_MPI_d2                     (16 files differ)
mww3_test_03/./work_PR1_MPI_d2                     (12 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2_c                     (17 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2_c                     (14 files differ)
mww3_test_03/./work_PR3_UNO_MPI_d2                     (18 files differ)
mww3_test_03/./work_PR2_UQ_MPI_d2                     (15 files differ)
mww3_test_03/./work_PR3_UNO_MPI_e_c                     (1 files differ)
mww3_test_03/./work_PR3_UQ_MPI_d2                     (15 files differ)
mww3_test_04/./work_PR1_MPI_d                     (3 files differ)
mww3_test_04/./work_PR2_UNO_MPI_d                     (3 files differ)
mww3_test_04/./work_PR3_UNO_MPI_d_c                     (3 files differ)
mww3_test_04/./work_PR3_UNO_MPI_d                     (3 files differ)
mww3_test_04/./work_PR3_UQ_MPI_d_c                     (3 files differ)
mww3_test_04/./work_PR3_UQ_MPI_d                     (3 files differ)
mww3_test_04/./work_PR2_UQ_MPI_d                     (3 files differ)
ww3_tp2.10/./work_MPI_OMPH                     (7 files differ)
ww3_tp2.16/./work_MPI_OMPH                     (4 files differ)
ww3_tp2.6/./work_ST0                     (3 files differ)
ww3_tp2.6/./work_ST4                     (3 files differ)
ww3_ufs1.2/./work_a                     (2 files differ)
ww3_ufs1.2/./work_c                     (3 files differ)
ww3_ufs1.2/./work_b                     (2 files differ)
ww3_ufs1.3/./work_a                     (3 files differ)

[mickaelaccensi]

Thanks Jessica !
I think test on MAPSTA .EQ. 1 is not needed because we only loop on ISEA points which are 'wet' points in my understanding
Do you see some differences in the output parameter UST and CHA ? If yes it could be good to see if it is improving the result

[JessicaMeixner-NOAA]

We do see a diff in ust:

***
/scratch1/NCEPDEV/climate/Jessica.Meixner/PR_WW3/bug01/regtests/output/ww3_tp2.6/work_ST0/ww3.201008_ust.nc_diff.txt
***
4055,4058c4055,4056
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
---
>     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, _, _, _, _, _, _, _, _, _, _, _, _, _,
>     _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, 1e-05,
4230,4233c4228,4229
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
---
>     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, _, _, _, _, _, _, _, _, _, _, _, _, _,
>     _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, 1e-05,
4405,4408c4401,4402
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
---
>     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, _, _, _, _, _, _, _, _, _, _, _, _, _,
>     _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, 1e-05,
4580,4583c4574,4575
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
<     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05, 1e-05,
---
>     1e-05, 1e-05, 1e-05, 1e-05, 1e-05, _, _, _, _, _, _, _, _, _, _, _, _, _,
>     _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, _, 1e-05,
4755,4758c4747,4748

Basically the same as the diffs that you see here: #1089 (comment)